Process of converting silver prints into color prints



Patented Nov. 6, i923.

WALTER LENGER, OF DESSAU, GERMANY, ASSIGNOR 'IO AGTIEN GESELLSCHAFT FITEANILIII FALBEIIKATION, OF BERLIN, GERMANY.

IROOESS GE CONVERTING SILVER PRINTS INTO COLOR PRINTS.

No Drawing.

To (ZZZ whom it may concern:

Be it known that I, IVALTER LENGER, a citizen of the German Republic,and a resident of Dessau, Germany (my P. 0. address being Ringstrasse22, Dessau, Germany), have invented certain new and useful Improvementsin Processes of Converting Silver Prints into Color Prints, of which thefollowing is a specification.

Letters Patent- No. 1,059,917 granted to Tauleigne and Marc, April 22,1913, and Letters Patent No. 1,093,503 granted to Tranbe, April 14:,191i, disclose the conversion of silver prints into color prints. Thesilver on the prints is transformed into compounds capable of beingcolored, such as silver iodide, silver bromide, silver chloride, silverterrocyanide, double compounds of silver and copper or double compoundsof Silver and mercury, and the prints are then colored, and thereaftertreat-ed with a mixture of fixing compounds and substances for producinginsoluble lakes with the dyestuffs used for coloring the prints.

The patent specification 1,093,503 indicates that silver iodide presentsthe greatest afiinity to colors, whereas the patent specification1,059,917 describes a particular step in the process which consists inthe treatment of the positive first with cupric chlorid and subsequently with potassium iodid.

The present invention relates to an improvement giving particularly goodresults. By this improvement the silver print is treated with neutralsolution of a quinone, such as benzoquinone and a naphthoquinone, in thepresence of an halogenide, such as an alkali metal halogenide. Thebrownish picture then, after having been washed for a short time, isdyed with a basic dyestufi and then if necessary cleared. The dyeconstituting the color picture may be transformed if desired in theknown manner for example by treating with tannine into an insolublelake. The silver picture remaining after dyeing may be eliminated ifdesired in a known manner by treating with dissolving agents.

It is advisable to subject weak prints to Serial No. 526,815.

this process as a remarkable intensifying takes place. The picturesespecially adapted for being projected are distinguished by their greatclearness and the deepness of color.

Thefollowing example may serve to illustrate my invention withoutlimiting it:

A developed, fixed and washed positive film is immersed for 10 minutesinto an aqueous solution containing per litre 5 g. or" benzoquinone and120 g. of potassium chloride. The film is then washed during 5 minutes,brought into a solution containing per litre of water 1 g. oftolusafranine and 5 g. of glacial acetic acid, washed again during 5minutes, cleared for a short time in a solution of sodium bisuliite of 2per cent strength and washed again.

In the example for 120 g. oi potassium chloride for instance the samequantity of sodium chloride may be replaced. The same result is obtainedwith 40 g. of potassium bromide. Asanother eflicacious bath for example10 g. of 1.2-naphthoquinone and 120 g. of potassium chloride per litermay be em ployed.

Having now described my invention and the manner in which it may beperformed What i claim 1s,-

1. In the process for. converting silver prints into color pictures theherein-described improvement, which consists in dyemg With basic dyessilver prints having undergone a treatment with a neutral solution of aquinone in the presence of a halogenide.

2. In the process for converting silver prints into. color pictures theherein-described improvement, which consists in dyeing with basic dyessilver prints having undergone a treatment with a neutral solution of aquinone in the presence of an alkali metal halogenide.

In testimony whereof I afiix my signature I in presence of twowitnesses. v

WALTER LENGER. Witnesses:

EMORY H. LORD, FRANK B. Wmmnormm.

